scholarly journals Novel Applicators for Local Microwave Hyperthermia Based on Zeroth-Order Mode Resonator Metamaterial

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
David Vrba ◽  
Jan Vrba
Keyword(s):  
Penetration Depth ◽  
Biological Tissue ◽  
Main Idea ◽  
Order Mode ◽  
Zeroth Order ◽  
Theoretical Limit ◽  
Full Wave ◽  
Em Field ◽  
Virtual Phantom ◽  
Mode Resonator

It is demonstrated that a theory of zero-order mode resonator (ZOR) metamaterial (MTM) structure can be used for the development of a novel class of applicators for microwave thermotherapy, for example, for hyperthermia in cancer treatment or for physiotherapy. The main idea of creating such an applicator is to generate and radiate a plane electromagnetic (EM) wave into the treated biological tissue, at least in a certain extent. The main aim of this paper is to investigate whether an EM wave generated by ZOR MTM structure and emitted into the biological tissue can produce a homogeneous SAR distribution in the planes parallel to the applicator aperture and achieve a penetration depth approaching the theoretical limit represented by SAR distribution and penetration depth of an ideal EM plane wave. EM field distribution inside a virtual phantom of the treated region generated by the applicator that is based on the proposed ZOR MTM principle is investigated using a well-proven full-wave commercial simulation tool. The proposed applicator type shows both a low unwanted leaked electromagnetic field and a fairly homogeneous electric field in its aperture as well as in the virtual phantom of the treated region.

Zeroth-Order-Mode Circular Microstrip Antenna With Patch-Like Radiation Pattern

2018 ◽  
Vol 17 (3) ◽  
pp. 446-449 ◽  
Author(s):  
Chaoqun Zhang ◽  
Jianqiang Gong ◽  
Yuanxin Li ◽  
Yuhao Wang
Keyword(s):  
Radiation Pattern ◽  
Microstrip Antenna ◽  
Order Mode ◽  
Zeroth Order ◽  
Circular Microstrip Antenna

scholarly journals Absorption by water increases fluorescence image contrast of biological tissue in the shortwave infrared

2018 ◽  
Vol 115 (37) ◽  
pp. 9080-9085 ◽  
Author(s):  
Jessica A. Carr ◽  
Marianne Aellen ◽  
Daniel Franke ◽  
Peter T. C. So ◽  
Oliver T. Bruns ◽  
...  
Keyword(s):  
Penetration Depth ◽  
Fluorescence Imaging ◽  
Biological Tissue ◽  
Ex Vivo ◽  
Scattered Light ◽  
Image Contrast ◽  
Fluorescence Image ◽  
Tissue Phantoms ◽  
Shortwave Infrared

Recent technology developments have expanded the wavelength window for biological fluorescence imaging into the shortwave infrared. We show here a mechanistic understanding of how drastic changes in fluorescence imaging contrast can arise from slight changes of imaging wavelength in the shortwave infrared. We demonstrate, in 3D tissue phantoms and in vivo in mice, that light absorption by water within biological tissue increases image contrast due to attenuation of background and highly scattered light. Wavelengths of strong tissue absorption have conventionally been avoided in fluorescence imaging to maximize photon penetration depth and photon collection, yet we demonstrate that imaging at the peak absorbance of water (near 1,450 nm) results in the highest image contrast in the shortwave infrared. Furthermore, we show, through microscopy of highly labeled ex vivo biological tissue, that the contrast improvement from water absorption enables resolution of deeper structures, resulting in a higher imaging penetration depth. We then illustrate these findings in a theoretical model. Our results suggest that the wavelength-dependent absorptivity of water is the dominant optical property contributing to image contrast, and is therefore crucial for determining the optimal imaging window in the infrared.

scholarly journals Compact Penta-Band Dual ZOR Antenna for Mobile Applications

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jae-Gon Lee ◽  
Dong-Jin Kim ◽  
Jeong-Hae Lee
Keyword(s):  
Dispersion Relation ◽  
Transmission Line ◽  
Mobile Applications ◽  
Double Negative ◽  
Zeroth Order ◽  
Resonant Frequencies ◽  
Good Efficiency ◽  
Broad Bandwidth ◽  
Full Wave ◽  
Band Stop Filter

A compact penta-band dual zeroth order resonator (ZOR) antenna with band-stop filter is proposed for mobile applications. The ZOR antenna is designed with modified mushroom-like structures extended on nonground region to obtain good efficiency and broad bandwidth. This modified mushroom-like structure is confirmed as double negative (DNG) transmission line by full wave simulated dispersion relation. Moreover, a bended patch and a band-stop filter (BSF) are employed to increase efficiency and bandwidth, respectively. The length of each antenna is aboutλ0/10at the resonant frequencies of 900 MHz and 1800 MHz, respectively. The overall dimension of the antenna is 54.4 mm (length) × 4 mm (width) × 5 mm (height). The total efficiencies in low and high bands are measured more than 40% and 70%, respectively.

scholarly journals An Eigenmode Study of Nanoantennas from Terahertz to Optical Frequencies

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2782
Author(s):  
Konstantinos D. Paschaloudis ◽  
Constantinos L. Zekios ◽  
Georgios C. Trichopoulos ◽  
Filippos Farmakis ◽  
George A. Kyriacou
Keyword(s):  
Penetration Depth ◽  
Patch Antenna ◽  
State Of The Art ◽  
The State ◽  
Antenna Design ◽  
Surface Currents ◽  
Rectangular Patch ◽  
Full Wave ◽  
Volume Currents

In this work, we present a rigorous full-wave eigenanalysis for the study of nanoantennas operating at both terahertz (THz) (0.1–10 THz), and infrared/optical (10–750 THz) frequency spectrums. The key idea behind this effort is to reveal the physical characteristics of nanoantennas such that we can transfer and apply the state-of-the-art antenna design methodologies from microwaves to terahertz and optics. Extensive attention is given to penetration depth in metals to reveal whether the surface currents are sufficient for the correct characterization of nanoantennas, or the involvement of volume currents is needed. As we show with our analysis, the penetration depth constantly reduces until the region of 200 THz; beyond this point, it shoots up, requiring volume currents for the exact characterization of the corresponding radiating structures. The cases of a terahertz rectangular patch antenna and a plasmonic nanoantenna are modeled, showing in each case the need of surface and volume currents, respectively, for the antenna’s efficient characterization.

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